ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Pull out fuse panel?
by wa2ise. 12/14/18 05:09 PM
Video door bell causing chime activation of coil
by gfretwell. 12/10/18 12:35 AM
Conduit fill Calculations
by gfretwell. 12/08/18 08:39 PM
Swimming Pool question
by HotLine1. 12/05/18 12:37 PM
Tingle off the water spigot
by rmiell. 11/30/18 01:03 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 12 guests, and 16 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
horizontal running lines? #160467
06/06/06 01:28 AM
06/06/06 01:28 AM
E
e57  Offline OP
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Keep gettting lines running up the screen on my CCTV, pulling my hair out. Connections clean and solid...
Just not getting it? Ideas?

[This message has been edited by e57 (edited 06-06-2006).]


Mark Heller
"Well - I oughta....." -Jackie Gleason
Study Guides for VDV / Structured Cabling Installers

Voice, Data, Video, (VDV) Fiber Optics, Communications, Low Voltage,
Fire Alarm, Electronic Security Systems Installations & Related

NTC Low Voltage Training & NICET Exam Study Guides
Low Voltage Training & NICET Exam Study Guides

Re: horizontal running lines? #160468
06/06/06 06:25 AM
06/06/06 06:25 AM
L
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
You have AC current running thru the video cable shield. The "ground" at the camera is slightly above or below the "ground" at the monitor. This can be fixed by using a video isolation transformer AKA ground loop isolation transformer.

LarryC

Re: horizontal running lines? #160469
06/06/06 02:20 PM
06/06/06 02:20 PM
H
hbiss  Offline
Member
Joined: Dec 2003
Posts: 886
Hawthorne, NY USA
It's 60Hz hum on the coax. If it were audio you would hear it, since it's video you see it. Look for ground loops.

-Hal

Re: horizontal running lines? #160470
06/07/06 12:10 AM
06/07/06 12:10 AM
J
JoeTestingEngr  Offline
Member
Joined: Nov 2005
Posts: 799
Chicago, Il.
OK, the world hansn't ended yet so I'm going to bore you with, yes, "VIDEO TRIVIA"
Back in the day, before that new-fangled color TV, vertical scan rate was 60Hz. The even and odd fields of 262.5 lines each, make up the 525 lines of a 30Hz frame. This design eliminated "flicker". 60Hz X 262.5 = 15750Hz, which was the horizontal scan rate. But now, with NTSC 3.58, the horizontal scan rate is really 15,734 Hz. and the vertical scan rate is really 59.94 Hz. That creates a .06Hz beat frequency with any AC hum. I would argue that the lines are walking up your screen more than running since it might take more than 8 or 16 seconds to make a round trip.

More trivia. The color burst frequency you always hear of as being 3.58MHz, is really 3.579545MHz. More importantly, four times that is 14.31818MHz. This frequency produces 70nS read and write clocks that are used in time base correctors and frame synchronizers used in the U.S.A. and other countries using NTSC 3.58. These are used in TV studios or post-production facilities to prevent nasty horizontal or color shifts. Video is written into memory using a write clock that is phase locked to the burst of the video source. It is read from memory using a read clock phase locked to a house reference. If everything is timed in correctly, the house is said to be in SC-H (subcarrier, horizontal) phase.

WAKE UP! This is something most will never hear about. You generally think of there being 30 frames of video. But for editing purposes, there are really 15 color frames a second. The frames are referred to as "A" & "B". If you do an edit between two sources as A,B,A,B/B,A,B,A,B..., you will get a nasty shift at the edit point. That is because the burst phase is 180 degrees out.

So what do the last two paragraphs have to do with your problem? Nothing! I'm just happy the world as we know it hasn't ended. I hear Heaven might use PAL or SECAM and I couldn't find work there. I had a similar problem to yours when I installed a sat. Rx. inside our existing audio facility and had to run video and audio to our new facility router. The video hum bar was terrible until I ran it through an equalizing distribution amplifier. I didn't really need the EQ. but it used an isolated BNC connector on the input and a differential amplifier. I posted this in a couple other threads. An isolation transformer on either the video source or monitor power supply would fix it. I don't think that transformers in the video path hold your answer if you're talking composite video.
Joe

Re: horizontal running lines? #160471
06/07/06 04:44 AM
06/07/06 04:44 AM
P
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Quote
I hear Heaven might use PAL


PAL introduces its own foibles for video editing though, as you have to allow for the"swinging color burst."

Re: horizontal running lines? #160472
06/07/06 07:14 PM
06/07/06 07:14 PM
L
LarryC  Offline
Member
Joined: Jul 2004
Posts: 783
Winchester, NH, US
This is just one source for Video Isolation transformers and isolation amplifiers.
http://www.21best.com/21_best/electronic/security/video/filters/for_sale_.html

Another approach is to isolate the video source that is causing the hum bars, from the local ground. THIS DOES NOT MEAN CUT OFF THE GROUND PIN! If it is a camera, mount the camera base on a piece of wood. If it is powered by a plug in power supply, check to see if there is a ground lift jumper or switch.

Verify that the earth grounds at the outlets feeding the video equipment are connected to the same grounding system and they are at the same potential to each other.

LarryC

Re: horizontal running lines? #160473
06/07/06 07:19 PM
06/07/06 07:19 PM
H
hbiss  Offline
Member
Joined: Dec 2003
Posts: 886
Hawthorne, NY USA
If it is a camera, mount the camera base on a piece of wood.

That may be all your problem is if the camera doesn't have a line cord. Is it a metallic mount and do the screws go into metal studs?

-Hal

Re: horizontal running lines? #160474
06/07/06 09:00 PM
06/07/06 09:00 PM
E
e57  Offline OP
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Been tearing hair out.....

Metal camera body on outside stucco, metal lathe, main panel mounted to stucco as well... Thats about when this started, with the addition of outside camera.

I'll let you know.....


Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: horizontal running lines? #160475
06/08/06 03:18 PM
06/08/06 03:18 PM
H
hbiss  Offline
Member
Joined: Dec 2003
Posts: 886
Hawthorne, NY USA
Just take the camera off the mount (have somebody hold it?) and see if the hum goes away.

-Hal

Re: horizontal running lines? #160476
06/09/06 01:21 AM
06/09/06 01:21 AM
E
e57  Offline OP
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
It was a power supply that got added for that camera, and the fact that i forgot to reground the rack when i moved stuff around.

Reground rack, most of it gone, swapout power supply... Fine....

The REGULATED power supply shows 120 Hz! Voltage to low for regulator cut off after rectifiers....


Mark Heller
"Well - I oughta....." -Jackie Gleason

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Posts: 165
Joined: March 2007
Show All Member Profiles 
Top Posters(30 Days)
Popular Topics(Views)
252,208 Are you busy
189,186 Re: Forum
178,871 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.046s Queries: 14 (0.020s) Memory: 1.0161 MB (Peak: 1.1895 MB) Zlib enabled. Server Time: 2018-12-15 07:55:07 UTC